ObjectiveTo investigate the effect of interleukin-33 defect on the polarization of peritoneal macrophages with the expressions of surface and inflammatory molecules from IL-33 knockout (IL-33-/-) mice.MethodspMφ was isolated from C57BL/6 wild type (WT) and IL-33-/-mice and divided into IL-33-/- group and WT group, then cultured in vitro for 48 hours; the mRNA of iNOS, Arg-1, IL-1, IL-10 and IL-12 were detected by real-time PCR.The secretion of IL-12, TNF-α, IL-10 and NO were detected by ELISA and Griess method respectively.The surface molecules (CD80, CD86, CD206, TLR4, TLR2, MHCⅡ) were analyzed by flow cytometry.ResultsThe expression of M1 marks (NO, MHCⅡand CD86) were increased (P＜0.01) in IL-33-/-mice compared with WT group ;the expression of TLR4 in pMφ from mice IL-33-/- group was higher than WT group (P＜0.05).ConclusionThe peritoneal macrophages were polarized to M1 direction in IL-33-/- mice.